Meniscal tears are frequent sources of disability, especially in persons with concomitant knee osteoarthritis (OA). Observational studies suggest that while arthroscopic partial meniscectomy (APM) consistently relieves symptoms and improves functional status in patients with symptomatic meniscal tear, the outcome of APM is decidedly worse in patients with coexisting OA. There has never been a clinical trial of the effectiveness of APM in patients with knee OA and concomitant symptomatic meniscal tear. Further, there is little evidence on the efficacy of nonoperative management in this setting. Thus, clinicians are uncertain about the short and long term benefits, drawbacks and indications for APM in OA patients with symptomatic meniscal tears. We propose a multicenter, randomized controlled trial of APM versus a standardized nonoperative program in patients with symptomatic meniscal tear and concomitant knee OA. The trial will be carried out in five outstanding centers. The study has three specific aims: Aim 1: To conduct a randomized controlled trial to compare the efficacy of APM versus a standardized non-operative management program among patients with symptomatic meniscal tear and knee OA. Aim 2: To follow the trial cohort for two years in order to determine whether differences between APM and nonoperative therapy in pain relief and functional improvement persist for two years. Aim 3: To evaluate the cost-effectiveness of APM in the management of patients with symptomatic meniscal tears in the setting of knee osteoarthritis. The trial will provide an evidence-based framework for effective and cost-effective clinical management of meniscal tears in the setting of knee OA, one of the most common clinical dilemmas affecting a large proportion of middle-aged and older persons in the US.Public Health Summary: Over 700,000 surgeries are performed each year for patients who have symptoms of a meniscal tear and who also have knee osteoarthritis. Presently, clinicians do not know whether this operation is better than nonoperative therapy. We propose a multicenter randomized controlled trial to rigorously compare these two approaches.